Hemostatic clips

ABSTRACT

Clips having pseudoelastic properties at body temperature are used to cause hemostatis of blood vessels located along the gastrointestinal tract. Methods for causing the hemostasis of blood vessels and ulcer beds using the clips of the present invention are also disclosed.

FIELD OF THE INVENTION

1. The present invention relates to hemostatic clips, and morespecifically, to pseudoelastic nitinol clips which are used to causehemostasis of blood vessels located along the gastrointestinal tract.

BACKGROUND OF THE INVENTION

2. Gastrointestinal bleeding is a somewhat common and serious conditionthat can be fatal if left untreated. This problem has prompted thedevelopment of a number of endoscopic therapeutic approaches to achievehemostasis, such as the injection of sclerosing agents and contactthermo-coagulation techniques. Although such approaches can beeffective, bleeding often continues for many patients and correctivesurgery therefore becomes necessary. Because surgery is an invasivetechnique that can be associated with many undesirable side effects,there exists the need for highly effective, less invasive procedures.

3. Mechanical hemostatic devices have been used in various parts of thebody, including gastrointestinal applications. Such devices aretypically in the form of clamps, clips, staples, sutures, etc. which areable to apply sufficient constrictive forces to blood vessels so as tolimit or interrupt blood flow. One of the problems associated withconventional hemostatic devices, however, is that they can only bedelivered using rigid-shafted instruments via incision or trocarcannula. Moreover, none of the conventional endoscopic hemostaticdevices are strong enough to cause permanent hemostasis.

4. In order to avoid the problems associated with conventionalhemostatic devices, the use of shape memory alloys has been proposed.For example, U.S. Pat. No. 4,485,816, hereby incorporated by reference,discloses the use of a shape memory surgical staple for use in holdingthe edges of a wound together while it heals. Similarly, U.S. Pat. No.5,002,563, hereby incorporated by reference, discloses the use of shapememory sutures.

5. Shape memory alloys (SMA's) have the ability to “remember” specificshapes which corresponds to particular metallurgical phases. Ifdeformed, SMA's can be heated or cooled to invoke a phasetransformation, which in turn, causes a transformation in shape. Shapememory alloys are characterized by a transition temperature ortransition temperature range, above which the predominant metallurgicalphase is termed austenite and below which the predominant phase istermed martensite. The transformation temperatures of SMA's are commonlydiscussed with reference to M_(s) , and M_(f), the martensitic start andfinish temperatures, respectively, and A_(s) and A_(f), the austeniticstart and finish temperatures, respectively. The transformation betweenthese phases is reversible such that when alloys are deformed into somefirst configuration while in the austenitic state, cooled into amartensitic state, deformed into a second configuration, and thenre-heated to the austenitic state, the alloy will revert back to thefirst configuration by virtue of the martensite-to-austenite phasetransformation.

6. PCT Publication No. WO 96/16603, hereby incorporated by reference,specifically discloses the use of shape memory materials to address theproblem of gastrointestinal bleeding. In this reference, a hemostaticstaple is employed to affect hemostasis of an actively bleeding pepticulcer. The staple makes use of the thermally-inducedmartensite-to-austenite transformation in shape memory nickel-titaniumalloys (“nitinol”), thus requiring the application or removal of heat tothe staple for deployment. One of the problems with this and similar SMAdevices is that the change in temperature necessary to induce therequired shape change can be procedurally difficult, and moreimportantly, can put the nearby tissue and surgical instrumentation atrisk. In addition, it can be difficult to manufacture SMA's with theprecise transformation temperatures necessary for surgical applications.It is therefore necessary to carefully monitor the temperature of suchdevices during shipping and storage so as to avoid phase transformationsduring this time. Moreover, the thermally-induced phase change may notproduce forces adequate to hemostatically close vessels or compresstissue.

7. The use of nitinol alloys having the ability to form stress-inducedmartensite as opposed to thermally-induced martensite has been used inmedical devices so as to avoid the potential problems of SMA devices. Insuch alloys, the reversible transformation between martensite andaustenite occurs by the application and removal of stress rather thanheat. Such alloys are characterized by an M_(d) temperature, which isgreater than A_(s) and represents the maximum temperature at whichstress-induced martensite can form. By deforming these alloys at atemperature between A_(s) and M_(d), the alloy transforms from itsaustenitic phase to a stress-induced martensitic phase. Upon release ofthe stress within this temperature range, the alloy reverts back to itsaustenitic phase and unstressed configuration. The property of nitinolwhich allows it to be deformed in its austenitic state so to cause atransformation to stress-induced martensite that is transformed back toaustenite by the release of stress is often termed “pseudoelasticity.”Strains of 8% or more are obtained in pseudoelastic nitinol, thus makingthis material useful for a wide range of applications where a largeamount of recoverable deformation is required.

8. U.S. Pat. No. 4,665,906, incorporated herein by reference, describessome medical devices which make use of pseudoelastic nitinol. In suchdevices, austenitic nitinol is deformed to form stress-inducedmartensite and held in its deformed configuration and martensitic stateby a restraining member. In this condition, the device is introducedinto the body, where it is removed from the restraining member to returnto its austenitic state and configuration.

SUMMARY OF THE INVENTION

9. The present invention is directed to hemostatic clips which exhibitpseudoelastic properties at body temperature. The clips of the presentinvention are able to compress tissue to cause the hemostasis ofbleeding blood vessels, particularly gastrointestinal bleeders. In oneembodiment of the present invention, the clips have a “U”-shapedconfiguration when in an undeformed state. In a second embodiment of thepresent invention, the clips have a circular-shaped configuration whenin an undeformed state. The present invention includes methods andsystems for causing the hemostasis of blood vessels and ulcer bedslocated along the gastrointestinal tract using hemostatic clips.

10. One advantage of the present invention is that it provides areliable, definitive treatment for the problem of gastrointestinalbleeding.

11. Another advantage of the present invention is that it can bedelivered via natural body orifices for the control of gastrointestinalbleeding.

12. Another advantage of the present invention is that it provideshemostatic clips which are deployed without the application or removalof heat.

13. Yet another advantage of the present invention is that it provideshemostatic clips with sufficient strength to produce permanenthemostasis when deployed.

14. Another advantage of the present invention is that it provideshemostatic clips which are particularly designed for application togastrointestinal bleeders.

BRIEF DESCRIPTION OF THE DRAWINGS

15.FIGS. 1A and 1B are plan views of a U-shaped hemostatic clip in afirst and second configuration, respectively, in accordance with thepresent invention.

16.FIG. 2 includes plan and cross-sectional views of a hypotube of thepresent invention.

17.FIGS. 3-5 illustrate a method of deploying the hemostatic U-shapedclips of the present invention.

18.FIG. 6 is a plan view showing an ulcer bed surrounded by hemostaticclips, in accordance with the present invention.

19.FIGS. 7A and 7B are plan and end views, respectively, of a deliverydevice used to deploy the U-shaped hemostatic clips of the presentinvention.

20.FIG. 7B is a plan view of a delivery device deploying the hemostaticclips of the present invention adjacent an ulcer bed.

21.FIGS. 8A and 8B are plan views of circular hemostatic clips of thepresent invention.

22.FIG. 9 is a plan view of a hypodermic needle of the presentinvention.

23.FIG. 10 is a plan view of a delivery device used to deploy thecircular hemostatic clips of the present invention.

24.FIGS. 11A-11D illustrate a method of deploying the hemostaticcircular clips of the present invention.

DETAILED DESCRIPTION

25. The present invention is designed to address the problemsencountered in conventional methods used to ligate blood vessels. Moreparticularly, the present invention is adapted to restrict blood flowwhich results in gastrointestinal bleeding.

26. The present invention includes hemostatic clips which make use ofpseudoelastic properties found in materials such as nitinol. Using theseproperties, the clips of the present invention are shaped into a firstconfiguration that is useful for ligating blood vessels, deformed to asecond configuration to facilitate placement to a desired locationwithin the body, and released from its deformed configuration to allow aspontaneous reversion towards the first configuration.

27. The pseudoelastic material used to make the hemostatic clips of thepresent invention is characterized by an A_(s) temperature less thanbody temperature and an M_(d) temperature greater than body temperature.A clip in accordance with the present invention is thus provided with afirst configuration in its austenitic state, which is deformed to asecond configuration to facilitate the placement of the clip around oradjacent to a bleeding blood vessel. The deformation of the clip fromits first configuration to its second configuration results in theformation of stress-induced martensite. The clip is held in its secondconfiguration until positioned to a target location along thegastrointestinal tract. When released from this second configuration,the clip is urged toward its austenitic state and corresponding firstconfiguration because A_(s) is less than body temperature and austeniteis therefore the stable metallurgical phase. In this way, the clipapplies sufficient constrictive forces to the bleeding blood vessel tocause hemostasis thereof.

28. The hemostatic clips of the present invention are of any suitableconfiguration. In a first embodiment of the present invention as shownin FIG. 1, however, hemostatic clip 10 is in the form of a U-shaped wirehaving first 11 and second 12 prongs, and rear member 13. The diameteror width of rear member is less than that of either of the first 11 orsecond 12 prongs. The first configuration of clip 10 as shown in FIG. 1Arepresents the shape of clip 10 when in its substantially austeniticstate. In this configuration, the distance between said first 11 andsecond 12 prongs is about 5-10 millimeters, preferably about 7millimeters. This dimensional range is specifically designed to addressthe problem of gastrointestinal bleeders. The cross-section of clip 10is preferably circular, although other cross-sectional shapes such asrectangular can be used.

29. To facilitate placement around or near a blood vessel, prongs 11 and12 are urged in an outward direction to achieve a second configurationas shown in FIG. 1B. The distance between prongs 11 and 12 in thissecond configuration can be up to 15 millimeters or more. When deformedinto the shape shown in FIG. 1B from the shape shown in FIG. 1A,U-shaped clip 10 undergoes at least a partial stress-inducedtransformation from austenite to martensite.

30. A device such as hypotube 20, as shown in FIG. 2, is used to holdU-shaped clip 10 in its second configuration while it is delivered to atarget location along the gastrointestinal tract. Hypotube 20 is made ofany suitable material, such as stainless steel.

31. Hypotube 20 includes first 21 and second 22 prongs having pointedends 23 and 24, respectively. Along the length of the inner sides offirst 21 and second 22 prongs are longitudinal slots 25. Along thelength of both sides of rear member 26 are transverse slots 27. Thewidth of slots 26 and 27 are wider than the width of rear member 13 ofU-shaped clip 10, yet more narrow than first 11 and second 12 prongs ofU-shaped clip 10. Such a configuration allows hypotube 20 to holdU-shaped clip 10 in its second configuration, while permitting thepassage of U-shaped clip 10 through hypotube 20.

32. After placing clip 10 in hypotube 20, it is inserted as part of adelivery device 30 into the gastrointestinal tract, preferably via anatural body orifice. Upon reaching a target location, the pointed ends23 and 24 of hypotube 20 are used to penetrate the gastrointestinal wall31 by advancing a first pusher bar 32 which is attached to hypotube 20,as shown in FIG. 3. Also shown in FIG. 3 is second pusher bar 33, whichrests against, but is not attached to, clip 10. Second pusher bar 33 isinserted through transverse slots 27 of hypotube 20 to contact clip 10.The length of prongs 21 and 22 are sufficient to ensure that the bloodvessel to be treated is positioned between the prongs 11 and 12 of clip10, or is within about one centimeter of the ends of prongs 11 and 12 ofclip 10. The rear member 26 of hypotube 20 remains outside of thegastrointestinal wall.

33. To deploy clip 10, hypotube 20 is withdrawn from thegastrointestinal wall 31 by retracting first pusher bar 32, as shown inFIG. 4. During the withdrawal of hypotube 20, second pusher bar 33remains extended so to keep clip 10 at the target location. As clip 10is released from hypotube 20, it is urged towards its austeniticconfiguration as shown in FIG. 4. When hypotube 20 is completelywithdrawn from the gastrointestinal wall 31, the contact between secondpusher bar 33 and clip 10 is broken as shown in FIG. 5.

34. The clips of the present invention are delivered by any suitableinstrumentation, as is known in the art. For delivery of the clips vianatural body orifices, which is the preferred method of delivery, it isusually necessary to deliver the clips with the aid of steerableendoscope to allow the physician installing the clips to visuallyexamine the target location. “Endoscope” is intended to include similarinstrumentation such as a gastroscope or duodenoscope.

35. In addition to causing the hemostasis of individual blood vessels,the present invention contemplates the use of hemostatic clips to causethe hemostasis of bleeding ulcer beds. In order to achieve thehemostasis of an ulcer bed, it is desirable to substantially surroundthe ulcer bed 60 with hemostatic clips 62, as shown in FIG. 6. This ispreferably achieved with two pairs of hemostatic clips 62, each pairbeing substantially parallel to each other yet orthogonal to the otherpair. The hemostatic clips 62 are deployed into the gastrointestinalwall 61 in the configuration shown in FIG. 6 so to reduce the flow ofblood to ulcer bed 60. Each of the clips 62 should be within about 5 mm,preferably about 2 mm, and most preferably about 1 mm from the edge ofulcer bed 60.

36. In order to achieve the configuration of clips shown in FIG. 6, itis necessary to manipulate the clip delivery device to properly orientthe clips prior to insertion. This can be done with steerableendoscopes, as are known in the art, provided that the clips aredeployed in regions of the gastrointestinal tract that are wide enoughto permit such manipulation (e.g., the stomach or lower bowel). Innarrow regions of the gastrointestinal tract (e.g., the duodenum),however, it may be necessary to use a delivery device in which the clipsare pre-loaded in the proper orientation. An example of such a device isshown in FIGS. 7A-7C. As shown in FIG. 7A, delivery device 70 comprisesan endoscope 71 having a sheath 72 ending in a collar 73 that houses thehemostatic clips. As shown in FIG. 7B, the clips 10 are oriented for thedeployment configuration as shown in FIG. 6. As is known in the art,endoscope 71 includes optics 74 and at least one light 75. Sheath 72 isused to house any wires, instrumentation, etc. necessary to deploy clips10 from collar 73. In addition, sheath 72 is optionally slidable aboutendoscope 71 to permit rotation of collar 73 and the corresponding axialpositioning of clips 10. Although U-shaped clips 10 are shown in FIG.7B, collar 73 is easily adapted for the deployment of hemostatic clipshaving a circular or other configuration. To deploy clips 10, endoscope71 is oriented so that the surface of collar 73 is adjacent thegastrointestinal wall 61 as shown in FIG. 7C. Clips 10 are thereafterinserted into the gastrointestinal wall 61 so as to substantiallysurround ulcer bed 60 in an arrangement as shown in FIG. 6.

37. In another embodiment of the present invention, the nitinolhemostatic clip of the present invention is in a substantially circularconfiguration when it is in a substantially austenitic state, as shownin FIG. 8. Circular clip 80 has a diameter of about 5-10 millimeters,and preferably about 7 millimeters when in its austenitic configuration.This dimensional range is specifically designed to address the problemof gastrointestinal bleeders. Circular clip 80 can have interlocking oradjoining ends 81, 82, as shown in FIG. 8A, or overlapping ends as shownin FIG. 8B.

38. To facilitate placement around or near a blood vessel, the ends ofcircular clip 80 are urged away from each other so that clip 86 achievessome second configuration that permits clip deployment. This secondconfiguration typically has a straightened or arc shape. When deformedinto this second configuration, circular clip 80 undergoes at least apartial stress-induced transformation from austenite to martensite.

39. A device such as hypodermic needle 90, as shown in FIG. 9, is usedto hold circular clip 80 in its second configuration while it isdelivered to a target location along the gastrointestinal tract.Hypodermic needle has an arc configuration and includes pointed end 91,base 92 and pusher bar 93. Hypodermic needle 90 is made of any suitablematerial, although stainless steel is preferred.

40. Circular clip 80 is delivered to a target location along thegastrointestinal tract by any suitable instrumentation, as is known inthe art. Circular clip 80 is preferably delivered with the deliverydevice shown in FIG. 10. Delivery device 100 includes a duodenoscope 101having side-mounted optics 102, at least one side-mounted light 103 andgrasper 104. Sheath 105, ending in collar 106, covers only part of thecircumference of duodenoscope 101 so as not to cover the optics 102,light 103 or grasper 104.

41. Delivery device 100 is used to deliver circular clip 80 by themethod shown in FIGS. 11A-11D. As shown in FIG. 11A, the delivery device100 is delivered to a target location along the gastrointestinal tract.Grasper 104 is used to grasp the gastrointestinal wall 31 and pull ittowards the duodenoscope 101. As shown in FIG. 11B, hypodermic needle 90penetrates the pulled portion of the gastrointestinal wall and isadvanced to a desired location while housing circular clip 80 and pusherbar 93. Circular clip 80 is released by retracting hypodermic needle 90from the pulled gastrointestinal wall while holding the clip 80 withpusher bar 93. After hypodermic needle 90 is fully retracted from thepulled gastrointestinal wall, pusher bar 93 is likewise retracted intocollar 106. The pulled gastrointestinal wall is then released and clip80 resumes its austenitic circular configuration as shown in FIG. 11D.

42. The mechanism by which hypodermic needle 90 and/or push bar 93 isadvanced from or retracted into collar 106 is any suitable mechanism asis known in the art. For example, this mechanism can include a pulleyand cable mechanism, a fluid pressure and piston mechanism, or a geardriven (e.g., rack and pinion) mechanism. A pulley and cable system,however, is preferred as it is the most simple of these systems.

43. The present invention provides a reliable, definitive treatment forthe problem of gastrointestinal bleeding. Moreover, the presentinvention provides hemostatic clips that are deployable via natural bodyorifices and without the manipulation of temperature. When deployed inaccordance with the present invention, the clips provide sufficientstrength to produce permanent hemostasis.

44. It will be obvious to those skilled in the art, having regard tothis disclosure, that other variations on this invention beyond thosespecifically exemplified here may be made. Such variations are, however,to be considered as coming within the scope of this invention as limitedsolely by the following claims.

What is claimed is:
 1. A gastrointestinal clip, comprising: a clipexhibiting pseudoelastic behavior at body temperature; whereby said cliphas sufficient strength to cause the hemostasis of a blood vessellocated along the gastrointestinal tract; wherein said clip comprisesnitinol characterized by an A_(s) temperature less than body temperatureand an M_(d) temperature greater than body temperature; and wherein saidclip has a substantially circular configuration when said nitinol is ina substantially austenitic state.
 2. The gastrointestinal clip of claim1 , wherein said clip has an inner diameter of about 5-10 millimeterswhen said nitinol is in a substantially austenitic state.